Field of the Invention
The present invention relates to residential and commercial irrigation systems, and more particularly to irrigation controllers that use evapotranspiration (ET) data in calculating and executing watering schedules.
Description of the Related Art
Electronic irrigation controllers have long been used on residential and commercial sites to water turf and landscaping. They typically comprise a plastic housing that encloses circuitry including a processor that executes a watering program. Watering schedules are typically manually entered or selected by a user with pushbutton and/or rotary controls while observing an LCD display. The processor turns a plurality of solenoid actuated valves ON and OFF with solid-state switches in accordance with the watering schedules that are carried out by the watering program. The valves deliver water to sprinklers connected by subterranean pipes. There is presently a large demand for conventional irrigation controllers that are easy for users to set up in terms of entering and modifying the watering schedules. One example is the Pro C® irrigation controller commercially available from Hunter Industries, Inc., the assignee of the subject application. The user simply enters the start times for a selected watering schedule, assigns a station to one or more schedules, and sets each station to run a predetermined number of minutes to meet the irrigation needs of the site. The problem with conventional irrigation controllers is that they are often set up to provide the maximum amount of irrigation required for the hottest and driest season, and then either left that way for the whole year, or in some cases the watering schedules are modified once or twice per year by the user. The result is that large amounts of water are wasted. Water is a precious natural resource and there is an increasing need to conserve the same.
In one type of prior art irrigation controller the run cycles times for individual stations can be increased or decreased by pushing “more” and “less” watering buttons.
Another conventional irrigation controller of the type that is used in the commercial market typically includes a seasonal adjustment feature. This feature is typically a simple global adjustment implemented by the user that adjusts the overall watering as a percentage of the originally scheduled cycle times. It is common for the seasonal adjustment to vary between a range of about ten percent to about one hundred and fifty percent of the scheduled watering. This is the simplest and most common overall watering adjustment that users of irrigation controllers can effectuate. Users can move the amount of adjustment down to ten to thirty percent in the winter, depending on their local requirements. They may run the system at fifty percent during the spring or fall seasons, and then at one hundred percent for the summer. The ability to seasonally adjust up to one hundred and fifty percent of the scheduled watering accommodates the occasional heat wave when turf and landscaping require significantly increased watering. The seasonal adjustment feature does not produce the optimum watering schedules because it does not take into consideration all of the ET factors such as soil type, plant type, slope, temperature, humidity, solar radiation, wind speed, etc. Instead, the seasonal adjustment feature simply adjusts the watering schedules globally to run a longer or shorter period of time based on the existing watering program. When the seasonal adjustment feature is re-set on a regular basis a substantial amount of water is conserved and while still providing adequate irrigation in a variety of weather conditions. The problem is that most users forget about the seasonal adjustment feature and do not re-set it on a regular basis, so a considerable amount of water is still wasted, or turf and landscaping die.
In the past, irrigation controllers used with turf and landscaping have used ET data to calculate watering schedules based on actual weather conditions. Irrigation controllers that utilize ET data are quite cumbersome to set up and use, and require knowledge of horticulture that is lacking with most end users. The typical ET based irrigation controller requires the user to enter the following types of information: soil type, soil infiltration rates, sprinkler precipitation rate, plant type, slope percentage, root zone depth, and plant maturity. The controller then receives information, either directly or indirectly, from a weather station that monitors weather conditions such as: amount of rainfall, humidity, hours of available sunlight, amount of solar radiation, temperature, and wind speed. The typical ET based irrigation controller then automatically calculates an appropriate watering schedule that may change daily based on the weather conditions and individual plant requirements. These changes typically include the number of minutes each irrigation station operates, the number of times it operates per day (cycles), and the number of days between watering. All of these factors are important in achieving the optimum watering schedules for maximum water conservation while maintaining the health of turf and landscaping.
Another device that can be occasionally found connected to an irrigation controller is a soil moisture sensor. There are many methods used, but most involve sensors containing spaced apart electrodes placed at root zone depth in the soil to sense the moisture levels in the soil and help control irrigation amounts. There is typically a threshold set manually by the user to determine the “wet” and “dry” levels for the soil and plant conditions. However, systems with a stand alone soil moisture sensor typically are used as a shutoff type device, and the sensor does nothing to tell the controller how much or when to irrigate. Typically the homeowner or irrigation professionals must initially set up and then adjust the irrigation periodically during the year to optimize the amount being applied.
While conventional ET based irrigation controllers help to conserve water and maintain plant health over a wide range of weather conditions they are complex and their set up is intimidating to many users. They typically require a locally mounted weather station having a complement of environmental sensors. Such locally mounted weather stations are complex, expensive and require frequent maintenance. Instead of receiving data from a locally mounted weather station, home owners and property owners can arrange for their ET based irrigation controllers to receive weather data collected by a private company on a daily basis and transmitted to the end user wirelessly, via phone lines or over an Internet connection. This reduces the user's up-front costs, and maintenance challenges, but requires an ongoing subscription expense for the life of the ET based irrigation controller. In addition, the user must still have a substantial understanding of horticulture to set up the ET based irrigation controller. For these reasons, most ET based irrigation controllers are set up by irrigation professionals for a fee. These same irrigation professionals must be called back to the property when changes need to be made, because the set up procedures are complex and not intuitive to most users. These challenges are limiting the sale and use of ET based irrigation controllers to a very small minority of irrigation sites. This impairs water conservation efforts that would otherwise occur if ET based irrigation controllers were easier to set up and adjust.